Manufacture of rubberlike materials



Patented .luly 11,1959

MANUFACTURE OF RUBBERLIKE MATERIALS Hans Paul Wagner, Atlanta, Ga.

No Drawing. Application January 19, 1945, Serial No. 573,634

8 Claims. 1

This invention relates to manufacture of rubber-like materials; and itcomprises a process of making synthetic materials having many of theproperties of natural rubber, which comprises preparing a sulfur-sulfidedispersion by mixing sulfur with an aqueous solution of an alkali metalmonosulfide in the proportions of about (L85 to 0.975 part of sulfide to1 part of sulfur, the temperature being held within the range of about80 to 210 F. and the maximum time of preparation varying correspondinglybetween about 6 hours to 60 minutes, reacting in a closed reactionvessel from about 1.1 to 1.25 parts of ethylene dichloride with thefreshly prepared sulfursulfide dispersion at temperatures within therange of about 140 to 210 F. in corresponding maximum reaction times ofabout 120 to 1G minutes, and recovering the resulting rubber irematerial from the reaction products. The invention also includes therubber-like material produced by the said process, said material bein aresilient product insolublein water and organic solvents, having atensile strength when compounded and cured ranging from about 700 to1800 pounds per square inch, a tear resistance of up to about 350pounds, a hardness of from about 45 to 90, and an elongation of fromabout 150 to 600 per cent, said material containing from about '72 to 77per cent of sulfur, having a brittle point ranging from about to -10 F.and a specific gravity of about 1.4 to 1.55, depending upon thecompounding ingredients, being noncorrosive and stable even uponheating, being substantially odorless and capable of being milled,compounded and otherwise treated in all respects like natural rubber;all as more fully hereinafter set forth and as claimed.

This application is a continuation-in-part of my two copendingapplications, Serial Numbers 489,690 (now abandoned), and 500,421 (nowabandoned), filed March 26, 1943 and August 28, 1943, respectively. Thepresent application describes a process which represents an extensionand, in some respects an improvement upon the processes described inthese prior applications.

Many different synthetic rubbers have been proposed in the art but nonehas been able to compete on a cost basis with natural rubber and veryfew have possessed physical properties, such as tensile strength,resiliency and tear resistance, which are comparable with naturalrubber. Most of these processes have required the use of complicated andexpensive corrosion-resistant equipment constructed of criticalmaterials, which has seriously delayed their manufacture.

I have discovered what appearsto be an ideal solution for thesedifiiculties in a process which is as simple as any which has beenproposed heretofore, and which at the same time requires less equipment.And my rubber can be produced at a fraction of the cost of priorsynthetic rubbers. Moreover the rubber produced by this new methodcompares favorably in physical properties with most of the priorsynthetic rubbers regardless of cost.

My new method comprises reacting together in a closed reaction vesselethylene dichloride with a solution or dispersion of sulfur in an alkalimetal monosulfide solution which is prepared in such fashion that theformation of polysulfides is prevented or at least reduced to aninsignificant amount. The temperature and time of heating are socontrolled that the solution produced is unstable and capable uponstanding of depositing substantially all of its sulfur content in excessof the monosulfide. This can be used as a test to determine thesuitability of a sulfur-sulfide solution for the production of my gum. Apolysulfide solution, in contrast, is stable and deposits little or nosulfur on standing. Polysulfide solutions are prepared usually byrefluxing a mixture of sulfur in a monosulfide solution for severalhours and an excess of caustic in the solution promotes the formation ofthe polysulfide. In contrast, in the making of my sulfur-sulfidedispersion, the mixture of sulfur and monosulfide solution should not beboiled and should be heated to a temperature and for a time onlysumcient to disperse the sulfur. When a maximum solution temperature of210 F. is employed, dispersion of the sulfur takes only about 20 to 30minutes. An open or closed vessel can be used. Surprisingly, I havefound that, if this dispersion is permitted to stand for a period ofabout 12 hours or more, it produces a decidedly inferior product even ifany sulfur deposited out of the solution is redispersed by heating. Inother Words, the sulfur-sulfide dispersion should be reacted with theethylene dichloride while in a freshly prepared condition. Anothersurprising fact is that the reaction with ethylene dichloride must takeplace in a closed reaction vessel i. e. under superatmospheric pressure,in order to produce a satisfactory product. The temperatures and timesemployed in this reaction should also be maintained as low and as shortas is consistent with economical operation. If the temperature duringthe reaction rises much above 210 F. and is maintained at thistemperature for any considerable period of time, for example, aninferiorproduct results.

It is my theory that the chemical reaction produced between ethylenedichloride and my fresh-- 1y prepared sulfur-sulfide dispersion involvesa reaction of the hydrosulfide group and sulfur, with the production ofa ring polymer. One manner in which such a reaction might take place isillustrated in the following equations:

N828 H20 2 NaSH NaOH H H 01-41-41-01 NaSH In the above equations, it isindicated that 3 molecules of ethylene dichloride combine with 3hydrosulfide groups and with 5 atoms of molecular sulfur. This agreeswith the fact that the product produced by this reaction containsapproximately 75 per cent sulfur.

While I am able as yet to offer no definite proof that the reactiontakes place as indicated, at least some support is given to the theorythat the hydrosulfide group is involved in the reaction by the fact thatthe end product reacts chemically with dithio carbamates. If the crudegum is reacted with these compounds, a soft product is produced and evenafter precuring, the dithio carbamates act as softeners or plasticizers.More important they produce an important stabilizing effect on theproduct and they substantially elim-- inatethe production oflachrymatory gases. It is, of course, well recognized that thesofteners, which are most effective in producing softening effects invarious plastics, usually have structures which are similar to those ofthe plastics. And since the dithio carbamates contain a hydrosulfidegroup this at least indicates that the reaction in question may involvea reaction of the hydrosulfide group.

That a fundamentally different reaction is involved than in theproduction of the so-called polysulfide plastics is shown clearly by theresults obtained in the following two comparative tests which wereconducted with the identical materials used in the same quantities, theonly difference being that in making the polysulfide plastic the sulfurwas boiled with the sodium sulfide solution to form a polysulfide priorto reacting the solution with the ethylene dichloride.

Example 1 New process.A mixer was employed which was equipped with aheating coil and having a capacity of 160 gallons. 80 gallons of waterwere introduced into this mixer and 265poundsof commercial sodiummonosulfide. were added, this procedure, this taking about 20 minutes.

4 monosulfide containing 61 per cent or 162 pounds of NazS, with sodiumthiosulfate and sodium carbonate being the principle impurities asidefrom water. The mixture was heated and agitated to dissolve the sulfidewhich took about 10 minutes. At this point 180 pounds of a commercial,ground flour of sulfur were added, analyzing 99 per cent sulfur. Heatingwas continued until the sulfur dispersed or dissolved, the temperaturebeing maintained at about 200 F. during this The solution was introducedinto a closed reaction vessel equipped with cooling coils and cooled to165 F. At this point 210.6 pounds of ethylene dichloride were added inquantities of about 1 gallon at a time, the solution being continuouslyagitated during this operation, and maintained under a pressure of from10 to 15 pounds. These additions were made over a period of about 1hour, durin which time the temperature was maintained at 165 F. A darkgreen subjacent layer was seen to form during the addition of theethylene dichloride and, on cooling, this layer separated cleanly. Thereaction vessel was then heated to higher temperatures to recover theexcess unreacted ethylene dichloride. The latter came over insubstantially pure condition and was recovered by condensation. When thepoint was reached that nothing but water came over, i. e. at atemperature of about 195 F., heating was discontinued. The aqueousliquor was decanted and the gum in the bottom of the vessel was removedand transferred to a standard rubber mill cracker, where it wasthoroughly washed with water. The resulting gum was found to beresilient and rubber-like in properties, stable upon aging and capableof being compounded by standard procedures. As explained in myacknowledged copending application, this gum after compounding andcuring can be heated up to about 350 F. withoutsoftening appreciably. Ifcompounded and then molded under a pressure of 1700 pounds per squareinch, it flows freely to fill all mold cavities and it can be reformedin this fashion several times without losing its favorable properties.The higher the molding pressure used the higher the density, tensilestrength and tear resistance of the molded product. Substantially nodisagreeable fumes are given off during molding. By proper compoundingwith carbon black etc. it is possible to produce materials havingtensile strengths as high as 1800 pounds per square inch, with tearresistances up to 350 pounds and elongations up to 600 per cent.

Example 2 Polysulfide process-In this process the same mixing vessel wasemployed and exactly the same chemicals, used in the same quantities asin the preceding process. But after the sulfur had been dispersed in thesulfide solution this solution was boiled'under a reflux for a period of3 hours to produce a polysulfide solution. This solution, which was madefrom gallons of water,'265 pounds of the same sodium sulfide and 180pounds of the same sulfur, differed from the sulfur-sulfide solutionused in Example 1 onlyby the fact that it had been boiled to produce apolysulfide. But when 210.6 pounds of ethylene dichloride wereintroduced into this solution in small proportions over a period ofabout an hour at a temperature of F. and at a pressure of 15 pounds,quite different results were produced.v The subjacent layer formed waslightv grenjn: color, rather; than darkizgreeni-r And; I

made it impractical,

torecover the ethyleneqdichloride and-,only a,..

small quantity came .over even. at 195 F., 1which is awell abo.ve the.boiling: point of ethylene dip.

chloride; Moreover .thevgum :recovered aftenthe aqueous liquor had beendecanted was quite.dif.

ferent: in properties from. the gum recovered in Example 1. This :gum,hadxaqconslstency com: parable torthat of. gellied 1. consomm; anditsphysical properties were notunlikethis material.

It was .not rubberyinycharacter; it flowed readily undergravity and.itpc-ouldbesqueezed. out bee. tween. the fingers. It.could;.not;be.worked on a. standard.. rubber:mill. cracker. It.wasmwashed. withzwaterzas: well as: possible inthe reaction vessel andthen dumped into another vesselior. testing.;.. a

It was found impossible to directly compare. the two freshly preparedmaterials; obtained in, Exampleszl .and:2: owing to:the fact .thatthemate? rial. of; Example 52.. could not be. compounded or worked:.owingto. its .non-elastic. properties. It wasso... soft. that itshardness.could not. be. measured. But. it wasfound that, if this material wasaged for about .four:weeks,itsihardness ine creased. to,such... anextent that..working.onv a cracker and.compounding was. possible; Forcomparative purposes. therefore,.a sample: from. Example l which. had;been aged. for four; weeks was. run thr.ough a .seriesof .testsincomparison. with :a sample-from Example. 2 which had been similarlyaged.

The .two aged samples were. compounded. by milling in. the. following.materials; in the. proportions.v indicated:

100 parts gum parts zinc oxide partfAlta-x) ('benzothiazyl disulfide)partstearic acid 30 partscarbon' black The stocks were pre-cured withlivev steam for 1 hour at pounds per square inch. Test samples 1 werepressedfor 10 minutes at 225 F. at 1200 pounds per square inch in amolding press. During the compounding procedure the material fromExample 2 evolved copious quantities of lachrymatoryases so thatcompounding was very difiicult and entirely impractical in commercial.practice, while the material, from Examplel, in contrast produced only aslight disagreeable odor.

These compounded samples were tested and the following comparativeresults were obtained:

Example 1 2 Example 2 Hardness 64 6O Tensile streng 900 875 Elongation507 525 .no tendency to agglomerate.

ethylene dichloride.

pounded material from rExamplewl had a hardeness;0fi65,-atensile'strengthof 915, andan elon-vgationofv 590). Butincontrast-the;.compound edmaterial from-Example 2 had a hardnessfofr 95..

It was approximatelyr'as, hardnashard rubber and wasequally asxbrittle.Its elasticity ,.and.all rubber-like properties had disappeared.

Therabove" resultstarebelieved to be-highly surprising. It wouldnormally beconsidered that the polysulfide solutionwould produce the'more' stable product, sincethe polysulfide solution itself is muchmorestablethan the sulfur-sulfide solutionusedinExample 1. In fact, ifthis sulfur-sulfide solution is. not'used within. about. 24

hours an inferior-product is produced. Butsure prisingly the materialfrom Example 1 iszsub-y.- stantiallystable while that .from- Example 2.$151 subject to rather rapid hardening upon; aging;

This isbelieved tordemonstrate therfundamentally differentchemical.reactions.;whichare produced in the two cases:

The: necessity-sfor. they use" ofta rclosed reaction vessel duringthereaction -of. the-:ethylene dichloride with the sulfuresulfideadispersion is shown by the following.exampleeinzwhich all.c0n-'- ditionsand chemicals employed were the same as in the preceding :twoexamples;except: for the use of a reflux, condenser. during. the; reaction"rather thana closed .reactionvesseh Example 3 Atmospheric pressureprocess. In this process a sulfur-sulfide dispersion was prepared usingthe same quantities of water, sodium sulfide and sulfur'and th'e'sameconditions asirr-Example 1. Thefreshly prepared dispersion wasintroduced into a vessel providedwith cooling coils and a refluxcondenser. The dispersion was cooled to F; and'210s6 pounds of ethylenedichloride were introduced into the vessel in small proportionsover aperiod of about an hour, the temperature being maintained at about 165F. and thepressure being atmospheric. The subjacent layer formed in thismanner was a light yellow, about the colorof sulfur. Thereaction vesselwas heated to recover the unreacted ethylene dichloride, as in Example 1and it was found that no substantial quantities of hydrogen sulfide wereevolved; as in Example 2. The aqueous liquor was decantedand the yellowmass removed from the bottom of the reaction vessel. This mass wasfound-to have arather porous structure and to be crumbly in nature.thermoplastic but only slightly resilient and had Its properties weresuch that it could not be washed on a standard rubber mill cracker. Andit could not be compounded since it would not agglomerate and form abank on the mill.

,- It is evident from the above examples that, in order to produce asatisfactory rubber-like product, it is necessary to employ mysulfur-sulfide dispersion in combination with the use of a closedreaction vessel during the reaction with The reason for this is, ofcourse, not fully understood.

I have found that many surprising results are more quickly than theso-called polysulfide plastics. Its pigment take-up is somewhat better:than:..natural rubber.. In-:some. casesstheiime It was 2.2 per centFe2O3 by analysis.

prdvement in properties upon compounding is truly astonishing. Ferricoxide (rouge) is an advantageous compounding agent. This is'believed tochemically combine with the gum. The

ferric oxide can be added either to the reactionmixture or in the millwith the production of substantially the same favorable results. Ifabout 5 per cent of ferric oxide is added to the sulfur-sulfidesolution, based on the weight of this solution, the gum obtainedcontains about This gum is considerably more elastic, it has greaterrebounce and faster recovery than gums produced without this addition.Substantially the same effect is produced if this quantity of ferricoxide is added on the mill. A still further increase in elasticity,rebounce and recovery is obtained if the addition offerric oxide isincreased up to a value of about 35 to 40 per cent. This product hasbeen found particularly useful for making printing rolls and plates andlike uses. The improvement noted upon the addition of ferric oxide isobtained when my' gum is compounded with from about 2 to 40 percent ofthe ferric oxide.

Carbon black can be compounded with my gum with advantageous results.Surprisingly up to 60 per cent of this compounding agent can be employedwith favorable results, although I normally employ only about 25 to 45per cent of this material. If 100 parts of my gum are compounded withparts of zinc oxide, part of benzthiazyl disulfide, /2 part of stearicacid and 60 parts of carbon black, the product will have a Shorehardness of about 90 but surprisingly it will have an elongation ofabout 150%; a tensile strength of from 1400 to 1500 pounds per squareinch and a tear resistance of 170 pounds.

Still more surprising results are obtained when my gum is subjected tothe same compounding but with the addition'of 2 /2 per cent ofpiperidinium pentamethylene dithiocarbamate after precuring for about 1hour under a steam pressure of about 60 pounds per square inch. The

resulting product has a hardness of 60, a tensile of 1600 to 1800 Poundsper square inch and elongation of 500 -to 600 per cent, a tearresistanceof 300 to 350 pounds and a brittle point of 10 F. Theseresults are highly unexpected and show the important plasticizing orsoftening results obtained by the use of nitrogen-substituteddithiocarbamates. I have found that any of the dithiocarbamates, whichare nitrogensubstituted with organic radicals, produce valuable effectsof this type. methylene dithiocarbamate, hexamethylene ammoniumhexamethylene dithiocarbamate and zinc N-dimethyldithiocarbamate forexample, have valuable plasticizing effects when compounded in my gum.The DuPont accelerator (piperidinium N pentamethylene dithiocarbamate)is another satisfactory compound of this type. From about 1 to 5 percent of these'compounds is effective. When 2 to 3 per cent ofpiperidinium pentamethylene dithiocarbamate is employed as plasticizingagent, my um is capable of passing the Government specification forsynthetic rubber. This specification requires the product to have anelongation of at least 100 per cent over the range of 0. to 150 F.

One of the most striking effects of the use of the above plasticizingagents is that they substantially eliminate the odor of my gum. Gassingin the mold is entirely eliminated. These compounds have anaccelerating'effect"whenused with natural rubbers Whereas in myigum theyPiperidinium N-pentahave a plasticizing or softening-effect andincidentally eliminateodor. They produce stocks which form very smoothsheets.

In one of my standard compounding procedures Iemploy 100 parts of gum to10 parts of zinc oxide, part of benzthiazyl disulfide, A. part ofstearic acid and from to per cent of carbon black. If it is desired tocoat a fabric with a skims'coatin'g of this gum, the quantity ofbenzthiazyl disulfide should be increased to 1% parts and the quantityof stearic acid to A part. This standard compounding procedure producesa product after curing with a tensile strength of about 1100 pounds persquare inch, a Shore hardness of 60-70 and an elongation of 300-500 percent. When 40 per cent carbon black is employed the corresponding valuesare 1200, 70-75 and 250-450 per cent, respectively, whereas when thecarbon black is replaced by 35 per cent ferric oxide, the correspondingvalues are 700-900, 70-75 and up to 700 per cent elongation,respectively.

It is desirable to employ a pre-curing step after the addition of thebenzthiazyl disulfide, zinc oxide and stearic acid. The carbon black canbe added either before or after the pre-curing step. This pre-curing maybe conducted by subjecting the gum to a live steam pressure ranging fromabout 40 to '70 pounds per square inch for a period'of about 90 to 30minutes. If a nitrogen substituted dithiocarbamate is used as asofteningagent, this is added after the precuring step, at which time the carbonblack may be incorporated. The pre-curing step tends to stabilize theproduct and eliminates all danger of gassing in the mold.

The characteristic properties of my gum can be summarized about asfollows: In the cold, the gum is insoluble in Water and all organicsolvents, showing no appreciable swelling even in cold acetone andcarbon disulfide. When compounded it has a specific gravity ranging fromabout 1.4 to 1.55, the latter value being obtained when compounded withiron oxide. has no definite melting point. When the crude gum is washedwith steam 6 times at 20 pounds pressure for 15 minutes, followed bydraining, the resulting product softens at a temperature ranging fromabout to C. Without this steam washing the material chars beforesoftening appreciably. The sulfur content ranges from about '72 to '77per cent, and is usually close to 75.5 per cent. When subjectedtoSoxhlet extraction for a period of severaldays, up to about 76.5 percent of the gum dissolves. But the residue is still rubbery in characterand contains approximately the original percentage of sulfur. Whencompounded and curedthe gum has a tensile strength ranging from about700 to 1800, a hardness ranging from about 45 to 90, an elongationranging from about 150 to 600%, a tear resistance ranging from 1'70 to350 pounds. Without the use of a dithiocarbamate plasticizing agent, itsnormal brittle point is about +5 F. It can be cured under pressure inthe mold and it can then be heated ,up to about 350 F. Without softeningappreciably.

While I have' described what I consider to be the best operatingembodiments of my invention, it is evident, of course, that variousmodifications can be made in the specific procedures disclosed withoutdeparting from the purview of this invention. As indicated in myacknowledged copending applications, best results are produced when thesultur sul'fi'de dispersion is made using 1 part ofsulfur tofrom about0.85 to 0.975 part of sodium sulfide and when the ethylene dichlorideis, employed in proportions ranging from about1,.1,to,1,.2.5 parts; Theoptimum proportion to employ is about;0.9 part of the sulfide to onepart of sulfur, andto 1.17 parts of ethylene dichloride. The proportionsof the reactants can, of course,bevariedoutside these ranges but theproducts thereby obtained are usually not as satisfactory. Duringthereaction it is important to agitatethereaction mixture rathervigorously. An agitator making from about 70 to 110 revolutions perminute is adequate. The size of the reaction vessel can be varied'widelyso long as the same degree of agitation is employed. One verysatisfactor way of agitating the: reaction vessel is to install a blowerin a circulating pipe leading from the gas space of the vessel to thebottom thereof. This blower sucks off vapors from the top of thereaction mass and forces them in at the bottom, preferably through aporous plate installed at this point. This method of agitation is moreeffective than the conventional stirring mechanisms and speeds up thereaction.

While it is usually advantageous to make up my sulfur-sulfide dispersionby heating to temperatures somewhat below 210 F., this solution can beprepared at lowertemperatures, such as 80 F. if sufilcient time isafforded to disperse the sulfur. The corresponding timerequired variesfrom about 1 to 6 hours. The conversion to polysulfides is not as rapidand hence the dispersion can be held for a longer time, such as 6 hours,at these lower temperatures. It is also true that, while temperatures of160 to 170 F. are the optimum to be used during the reaction between thesulfur-sulfide dispersion and the ethylene dichloride, it is possible toextend this temperature range considerably on both sides. At the lowertemperatures the reaction is slow and may take 120 minutes or more whileat the higher temperatures the reaction is almost instantaneous and canbe completed within 10 minutes or even 5 minutes. At the highertemperature it is difficult to hold the temperature of the reactionvessel within limits, since the reaction is highly exothermic. It isalso true that it is not advisable to extend the time of reaction anylonger than necessary at these high temperatures since there is somedanger of the formation of polysulfides during the reaction. It is forthese reasons that I prefer to operate within the temperature range of160 to 170 since at these temperatures the reaction is rapid but notviolent and the temperature can be controlled by the use of a reasonableamount of cooling water.

Any alkali metal monosulfide can be employed in the process to make thesulfur-sulfide dispersion. The sulfur may be employed in any form but,of course, the more finely divided it is, the more readily it goes intodispersion. The quantity of water employed in the process can be variedbut it is advantageous to employ minimum quantities in order thatsmaller reaction equipment may be employed. The sulfur-sulfidedispersion, therefore should be substantially saturated. In making upthe sulfur-sulfide disper sion the sulfur and sulfide may be addedsimultaneously to the water although the sulfur does not becomedispersed until the sulfide has dissolved.

My gum can be compounded with any of the usual compounding agents, asell as it th usual anti-oxidants, accelerators, deodorizing agents,reinforcing agents, softeners, fi1lers, etc. Non-freezing oils can beused to lower its brittle point. It is suitable for use in recappingtires, making rubber stamps, making bullet-proof gasoline tanks and forpractically all of the conventional uses of natural rubber. Othermodifications of my invention which fall within the scope of thefollowing claims will be immediately evident to those skilled in thisart.

What I claim is:

1. In the production of rubber-like products, the process whichcomprises dispersing about 1 part of sulfur in an aqueous solutioncontaining about 0.9 part of sodium monosulfide, while heating thesolution to a temperature within the range of to 210 F. for a time onlysufficient to disperse the sulfur, transferring the freshly preparedsolution to a closed reaction vessel and gradually adding about 1.17parts of ethylene dichloride while maintaining the temperature withinthe range of 160 to 170 F. and the pressure within the range of 7 to 20pounds, the addition of ethylene dichloride being continued over aperiod not substantially exceeding minutes, and recovering therubber-like product thereby produced.

2. In the production of rubber-like materials, the process whichcomprises, dispersing sulfur in an aqueous sodium monosulfide solutionby agitating and heating toa temperature ranging from 80 to 210 F. for atimeonly suiiicient to disperse the sulfur, from about 0.85 to 0.975part of sodium monosulfide being employed to 1 part by weight of thesulfur, and reacting the resulting sulfur-sulfide dispersion while infreshly prepared condition with from 1.1 to 1.25 parts by weight ofethylene dichloride in a closed reaction vessel operating atsuperatmospheric pressures of from 7 to 20 pounds per square inch and attemperatures within the range of 140 to 210 F., the reaction takingplace within a corresponding time period not substantially exceeding to10 minutes, and recovering the rubber-like product thus produced.

3. The process of claim 2 combined with the further step of compoundingthe rubber-like product with a suflicient amount of a dithiocarbamatewhich is nitrogen-substituted with an organic radical and which isselected from a group consisting of piperidinium pentamethylenedithiocarbamate, hexamethylene ammonium hexamethylene dithiocarbamateand zinc N-dimethyldithiocarbamate, to produce softening of the product.

4. The process of claim 2 combined with the further step of compoundingthe rubber-like product with a sufficient amount of piperidiniumpentamethylene dithiocarbamate to produce softening of the product.

5. The process of claim 2 wherein the reactants are employed in theproportions of about 0.9 part of monosulfide and 1.17 parts of ethylenedichloride to 1 part of sulfur.

6. The process of claim 2 combined with the further step of compoundingthe rubber-like product with a sufficient amount of pipenidiniumpentamethylene dithiocarbamate to soften the same and from 25 to 45 percent of carbon black.

7. A rubber-like composition of matter resulting from the process ofdispersing sulfur in an aqueous sodium monosulfide solution by agitatingand heating to a temperature ranging from 80 to 210 F. for a time onlysufficient to disperse the sulfur, from about 0.85 to 0.975 part ofsodium monosulflde being employed to 1 part by weight of the sulfur, andreacting the resulting sulfur-sulfide dispersion while in freshlyprepared condition with from 1.1 to 1.25 parts by weight of ethylenedichloride in a closed reaction vessel operating at superatmosphericpressures of from '7 to 20 pounds per square inch and at temperatureswithin the range of 140 to 210 F., the reaction taking place within acorresponding time period not substantially exceeding 120 to minutes,and recovering the rubber-like product thus produced.

8. A rubber-like composition of matter resultin from the process ofdispersing about 1 part of sulfur in an aqueous solution containingabout 0.9 part of sodium monosulfide, while heating the solution to atemperature within the range of 80 to 210 F. for a time only suflicientto disperse the sulfur, transferring the freshly prepared solution to aclosed reaction vessel and gradually adding about 1.17 parts of ethylenedichloride while maintaining the temperature within the range of 160 to170 F. and the pressure within the range of 7 to pounds, the addition ofethylene dichloride being continued over a period not substantiallyexceeding 90 minutes, andrecovering the rubber-like product therebyproduced.

HANS PAUL WAGNER.

REFERENCES CITED The following references are of record in the fle ofthis patent:

12 UNITED STATES PATENTS Number Name Date 1,854,423 Patrick Apr. 19,1932 1,854,480 Mnookin Apr. 19, 1932 1,890,191 Patrick Dec. 6, 19321,923,392 Patrick Aug. 22, 1933 2,026,875 Ellis et a1. Jan. 7, 19362,050,583 Orthner Aug. 11, 1936 2,174,000 Hills et a1 Sept. 26, 19392,195,380 Patrick Mar. 26, 1940 2,206,642 Patrick July 2, 1940 2,363,614Patrick Nov. 28, 1944 2,379,464 Thies 1 July 3, 1945 2,392,402 PatrickJan. 8, 1946 FOREIGN PATENTS Number Country Date 423,444 Great BritainFeb. 1, 1935 446,173 Great Britain Apr. 20, 1935 OTHER REFERENCES Kusteret a1.: Zeitschrift fur Anorganische Chemie, v01. 43, 1905, pages 53,56, 57, 58, 59, 71.

Mellor, Comprehensive Treatise on Inorganic and Theoretical Chemistry,vol. 2, page 629, published by Longmans, N. Y., 1922.

Barron, Modern Synthetic Rubbers, published by Van Nostrand, N. Y.,1944, 2nd ed., pages 272-289 and figure facing page 275.

Thiokol Facts, vol. 2, N0. 3, Aug. 1942, pages 1-7 and 10, published byThiokol Corp., Trenton, New Jersey.

2. IN THE PRODUCTION OF RUBBER-LIKE MATERIALS; THE PROCESS WHICHCOMPRISES DISPERSING SULFUR IN AN AQUEOUS SODIUM MONOSULFIDE SOLUTION BYAGITATING AND HEATING TO A TEMPERATURE RANGING FROM 80* TO 210*F. FOR ATIME ONLY SUFFICIENT TO DISPERSE THE SULFUR, FROM ABOUT 0.85 TO 0.975PART OF SODIUM MONOSULFIDE BEING EMPLOYED TO 1 PART BY WEIGHT OF THESULFUR, AND REACTING THE RESULTING SULFUR-SULFIDE DISPERSION WHILE INFRESHLY PREPARED CONDITION WITH FROM 1.1 TO 1.25 PARTS BY WEIGHT OFETHYLENE DICHLORIDE IN A CLOSED REACTION VESSEL OPERATING ATSUPERATMOSPHERIC PRESSURES OF FROM 7 TO 20 POUNDS PER SQUARE INCH AND ATTEMPERATURES WITHIN THE RANGE OF 140* TO 210* F., THE REACTION TAKINGPLACE WITHIN A CORRESPONDING TIME PERIOD NOT SUBSTANTIALLY EXCEEDING 120TO 10 MINUTES, AND RECOVERING THE RUBBER-LIKE PRODUCT THUS PRODUCED.